Method and Electronic Circuit Assembly for the Redundant Signal Processing of a Safety-Relevant Application, Motor Vehicle Brake System, Motor Vehicle Having Said Motor Vehicle Brake System, and Use of Such an Electronic Circuit Assembly

ABSTRACT

The invention relates to a method for the redundant signal processing of a safety-relevant application, in particular of a safety control unit of a motor vehicle, wherein at least two redundant signals are fed from at least one sensor ( 4 ) to an electronic circuit assembly ( 2 ) as input signals ( 6 ) for processing of the sensor information. At least one input signal ( 6 ) is converted into a different test signal ( 16 ). In the electronic circuit assembly ( 2 ), the one or more input signals ( 6 ) are fed to a first peripheral module ( 12 ) of a microcontroller ( 10 ), and the test signal ( 16 ) is fed to an additional peripheral module ( 18 ) of the microcontroller ( 10 ). The sensor information of the input signals ( 6 ) and of the test signal ( 16 ) are thus redundantly processed independently of each other in a respective peripheral module ( 12, 18 ) of the microcontroller ( 10 ). The invention further relates to an electronic circuit assembly ( 2 ) for performing such a method, a motor vehicle brake system, a motor vehicle having said brake system, and a use of such en electronic circuit assembly.

The invention relates to a method for the redundant signal processing of a safety-relevant application, in particular of a safety control unit of a motor vehicle, according to the preamble of claim 1, and to an electronic circuit arrangement for carrying out such a method, according to the preamble of claim 2. The invention further relates to a motor vehicle brake system and a motor vehicle having such an electronic circuit arrangement, and a use of this electronic circuit arrangement.

Electronic motor vehicle control devices, such as, for example, ABS and/or EBS brake control devices, often comprise redundant signal processing systems in order to be suitable for modern safety-relevant applications. In this case, the requirements on the components are steadily increasing. As the complexity of the individual components increases, however, so does the possibility of malfunctions. Due to the increasing requirements on the components, for example, control devices, said components are produced according to specified safety regulations.

One example of an antilock vehicle brake system is known from DE 32 34 637 C2. In this case, the input data are fed in parallel to two identically programmed microcontrollers and are synchronously processed there. The signals are compared in-between and at the output. If a deviation of the signals from one another occurs, a shut-off signal is output. Due to a second microcontroller, which is identical to the first microcontroller in terms of its design and its programming, at least some data processing errors can be detected. Such a system requires two high-quality microcontrollers, however, even though a single microcontroller would suffice for generating the actual control signals, whereby the expenditure for microcomputers doubles due to safety reasons.

In order to rule out a possible source of errors due to a systematic design error or a systematic production error of the microcontroller, the two systems would also have to be developed by independent programmers, whereby the expenditure increases even further.

The problem addressed by the invention is therefore that of creating a simple and cost-effective method and an electronic circuit arrangement with which malfunctions of the system can be detected with the reliability required for safety-relevant applications.

The problem is solved by the invention with the features of a method for redundant signal processing according to claim 1, with an electronic circuit arrangement according to claim 2, with a motor vehicle brake system according to claim 6, with a vehicle according to claim 7, and with a use of an electronic circuit arrangement according to claim 8.

In order to carry out the method for the redundant signal processing of a safety-relevant application according to the invention, such as, for example, an ABS or EBS control device of a motor vehicle, at least two redundant signals are fed from at least one sensor to an electronic circuit arrangement as input signals for the processing of the sensor information.

Preferably, the input signals are provided by two independent sensors in order to detect errors in the generation of the sensor signal due to a faulty sensor or to ensure the functional reliability of the system in the event of failure of one sensor.

The transmission device for transmitting the sensor signals likewise has a redundant design, in order to detect possible transmission errors. Therefore, according to the invention, at least two sensor signals are available to the electronic circuit arrangement as input signals for the processing of the sensor information. The input signals are transmitted to a peripheral module of a microcontroller either directly or via a protective circuit against overvoltage. Preferably, the peripheral module comprises a software module, which is designed to compare the received signals with each other. Possible sources of errors can be ascertained on the basis of present deviations, and the safety-relevant application can be transferred into a safe state.

The aforementioned, functionally independent paths via the two redundant input signals can be simultaneously influenced, however, if a systematic design error or a systematic production error is present in the peripheral module of the microcontroller. This error could influence both input signals simultaneously and result in a simultaneous failure or a malfunction of the system.

In order to minimize the risk of malfunctions of safety-relevant electronic circuit arrangements, according to the invention, at least one input signal is converted into a test signal. To this end, the electronic circuit arrangement comprises at least one input circuit, which is designed to generate a test signal from the input signal, which test signal differs from the input signal but retains the sensor information.

The test signal, as is likewise the case with the one or more input signals, is fed to the microcontroller for processing. Since the test signal differs from the input signal, the respective peripheral modules are also differently designed, and the test signal is processed in an additional peripheral module independently of the input signal, whereby the processings of the sensor information is advantageously made redundant. Since the peripheral modules meet the same processing goal, the signals or data can be compared after the processing, and possible systematic errors within the peripheral modules can be detected.

According to a preferred embodiment of the invention, the peripheral modules of the microcontroller for the redundant signal processing comprise software modules, which differ from one another, having different software drivers. It is therefore advantageously possible to avoid malfunctions or failures of the system resulting from faulty programming.

In another preferred embodiment of the invention, the input circuit, which converts the input signal into an analog test signal, is designed as a low-pass filter if the input signal is a pulse-width modulated signal. Alternatively, the input circuit, which converts the input signal into a pulse-width modulated test signal, comprises a voltage-controlled oscillator (VCO) if the input signal is an analog voltage or current signal. By means of such input circuits, available input signals can be particularly easily converted into different signals in order to permit these to then be redundantly processed by two independent, different peripheral modules.

Another preferred embodiment of the invention provides means for detecting significant deviations between the results of the redundantly processed sensor information of the input signal and of the test signal. If such deviations are present, the control systems affected by the deviating data can be advantageously transferred into a safe state. It is therefore advantageously possible to avoid wrong decisions by systems, which can possibly pose a danger to the person.

The aforementioned problem is further solved with a motor vehicle brake system, for example, an ABS or EBS system, with means for carrying out the method according to the invention, and/or with at least one electronic circuit arrangement according to the invention, in particular a safety control unit.

In addition, the aforementioned problem is solved with a motor vehicle, which comprises at least one electric circuit arrangement, in particular a safety control unit, for redundant signal processing, and/or a motor vehicle brake system having such an electronic circuit arrangement, and/or means for carrying out a method according to the invention for the redundant signal processing of a safety-relevant application.

Finally, the aforementioned problem is solved by a use of an electronic circuit arrangement according to the invention for the redundant signal processing of a safety-relevant application, wherein the electronic circuit according to the invention for redundant signal processing can be used in a motor vehicle brake system and/or in a motor vehicle.

Such a use of a circuit arrangement according to the invention advantageously ensures the functional safety of a system, in particular of a motor vehicle brake system or of a motor vehicle having electronic components.

Further embodiments of the invention will become apparent from the claims and from the exemplary embodiments explained in greater detail with reference to the drawing. In the drawing:

FIG. 1 shows a block diagram of an electronic circuit arrangement comprising a sensor system and a transmission device.

FIG. 1 schematically shows a redundantly operating system comprising an electronic circuit arrangement 2, which has at least one control functionality.

It is known to provide safety devices, with which errors occurring in the system can be detected, in electronic circuit arrangements, such as, for example, control devices for motor vehicle brake systems. When such an error is detected, suitable countermeasures can be implemented and the control device can be shut off or switched into an emergency mode. In order to detect errors, safety-relevant circuit components are often redundantly designed, i.e., in multiples. A corresponding comparison of the functions of the circuit components present in multiples reveals possible errors.

Therefore, in FIG. 1, a sensor system 4 is provided with two sensors, which detect the same measured variable independently of each other. The sensor information of the two sensors is contained in two received signals 6, which are transmitted to the electronic circuit arrangement 2 via a transmission device, for example, via two separate bus systems.

The input signals 6 are initially fed to two input circuits 8 of the electronic circuit arrangement 2. The input circuits 8 are intended only for protection against possible overvoltages, however, and are therefore considered optional, and so the input signals 6 are transmitted to a microcontroller 10, in particular to a first peripheral module 12 of the microcontroller 10.

In the exemplary embodiment shown in FIG. 1, the received signals 6 are pulse-width modulated signals of the sensor system 4. The sensors sense, for example, the displacement of the brake pedal and output this as a pulse-width modulated electric signal.

The first peripheral module 12 is preferably a reception/comparison unit, which can receive and compare signals. By means of the comparison of the input signals 6, the transmission device is checked for possible errors.

The first peripheral module 12 further comprises a first software module having an associated software driver, with which a braking demand is ascertained from the sensor information and a corresponding release of the pressure control is carried out.

However, if the first peripheral module 12 has a systematic error, for example, faulty programming of the first software module, a malfunction of the system, in particular of the microcontroller 10, can result despite the redundant transmission of the sensor information.

In order to rule out such singular causes of error (common cause failure—CCF), which can simultaneously influence functionally independent paths in a system, an input signal 6 is converted in an additional input circuit 14 into a test signal 16.

According to the exemplary embodiment in FIG. 1, the additional input circuit 14 is a low-pass filter, with which the pulse-width modulated input signal 6 is converted into an analog test signal 16. The test signal 16 therefore differs from the input signal 6 but still contains all the sensor information.

For the further processing of the test signal 16, said test signal is transmitted to a second peripheral module 18 of the microcontroller 10. The second peripheral module 18 is intended for the redundant signal processing of the microcontroller 10, i.e., the first peripheral module 12 and the second peripheral module 18 have the same processing goal.

Since the test signal 16 differs from the input signal 6, however, the second peripheral module 18 uses a second software module, which differs from the first peripheral module 12, and a different software driver for the further processing of the sensor information. Preferably, the second peripheral module 18 is essentially an analog-digital converter with subsequent processing of the digital signal.

A subsequent comparison of the ascertained braking demand of the first peripheral module 12 with the ascertained braking demand of the second peripheral module 18 advantageously makes it possible to detect a singular cause of error in one of the peripheral modules 12, 18 if the result of the redundant signal processing of the two peripheral modules 12, 18 differs significantly from one another.

The invention is not limited to the above-described exemplary embodiment, however. Alternatively, instead of the pulse-width modulated input signals 6, it is also possible to transmit two redundantly transmitted, analog current or voltage signals as input signals 6 to the electronic circuit arrangement 2. These analog current or voltage signals represent, for example, the braking pressure to be generated, which is specified via the actuation of the brake pedal.

If analog input signals 6 of the electronic circuit arrangement 2 are present, these are processed in a first peripheral module 12, with the goal of releasing the pressure control if the received signals 6 were transmitted without error.

A physically different test signal 16 is then generated from the analog input signal 6 in the additional input circuit 14. For example, the test signal 16 is a pulse-width modulated signal, which is generated by means of a voltage-controlled oscillator and is transmitted to the second peripheral module 18 for further processing.

Instead of a pulse-width modulated signal, it is also possible to provide additional types of modulation, such as, for example, pulse-frequency modulation, pulse-amplitude modulation, pulse-code modulation, or pulse-phase modulation, or any other type of modulation, such as, for example, amplitude modulation, angle modulation, or frequency/phase modulation, in order to transmit and/or convert the sensor signals.

In theory, it is possible to transmit any type of input signals 6 to an electronic circuit arrangement 2, wherein at least one input signal is converted into a different test signal 16.

In order to ensure the functional safety of the system, in particular of the motor vehicle brake system, according to the invention, in addition to the redundant transmission device for ensuring an error-free transmission of sensor signals, the software and hardware used in the microcontroller 10 for processing the sensor signals is also checked in terms of error-free function, by converting the input signal 6 into another test signal 16 and the subsequent evaluation of the received signal 6 in a peripheral module 12 and the evaluation of the test signal 16 in an independent peripheral module 18 are carried out separately.

A high level of safety of the system can therefore be achieved with the aid of the circuit arrangement 2 according to the invention. In this case, the circuit arrangement 2 according to the invention can be advantageously realized with little production expenditure, since only one microcontroller 10 is used.

The invention therefore complies with the new ISO (International Organization for Standardization) standard 26262 (“Road Vehicle—Functional Safety”), which is intended to ensure the functional safety of an electric or electronic system in motor vehicles.

All the features mentioned in the preceding description and in the claims can be combined individually, or in any combination thereof, with the features of the independent claims. The disclosure of the invention is therefore not limited to the described or claimed combinations of features. Instead, all combinations of features which are reasonable within the scope of the invention should be considered to be disclosed. 

1. A method for the redundant signal processing a safety-relevant application, in particular of a safety control unit within a motor vehicle, wherein at least two redundant signals are fed from at least one sensor (4) to an electronic circuit arrangement (2) as input signals (6) for the processing of the sensor information, at least one input signal (6) of which is processed in a peripheral module (12) of a microcontroller (10) of the electronic circuit arrangement (2), characterized in that at least one input signal (6) is converted into a test signal (16), wherein the test signal (16) differs from the input signal (6) but retains the sensor information, the test signal (16) is fed to an additional peripheral module (18) of the microcontroller (10) for the processing of the sensor information of the test signal (16), and the processing of the sensor information of the input signal (6) in a peripheral module (12) of the microcontroller (10) and the processing of the test signal (16) in an additional peripheral module (18) of the microcontroller (10) are carried out redundantly, independently of each other.
 2. An electronic circuit arrangement, in particular of a safety control unit of a motor vehicle, for the redundant signal processing for safety-relevant applications, comprising at least one microcontroller (10) having at least one peripheral module (12) for the processing of at least one received signal (6) of at least one sensor (4), characterized by at least one input circuit (14), which is designed to convert an input signal (6) of the circuit arrangement (2) into a test signal (16), wherein the test signal (16) differs from the input signal (6), and at least one additional peripheral module (18) of the microcontroller (10), which is designed to process sensor information contained in the test signal (16), wherein the processing of the sensor information of the input signal (6) in a peripheral module (12) of the microcontroller (10) and the processing of the test signal (16) in an additional peripheral module (18) of the microcontroller (10) are carried out redundantly, independently of each other.
 3. The electronic circuit arrangement as claimed in claim 2, characterized in that the peripheral modules (12, 18) of the microcontroller (10) for the redundant signal processing comprise software modules, which differ from each other, having different software drivers.
 4. The electronic circuit arrangement as claimed in claim 2 or 3, characterized in that the input circuit (14), which converts the input signal (6) into an analog test signal (16), is a low-pass filter if the input signal (6) is a pulse-width modulated signal, or the input circuit (14), which converts the input signal (6) into a pulse-width modulated test signal (16), comprises a voltage-controlled oscillator (VCO) if the input signal (6) is an analog voltage or current signal.
 5. The electronic circuit arrangement as claimed in one of claims 2 to 4, characterized in that, in the case of significant deviations between the redundantly processed sensor information of the input signal (6) and of the test signal (16), the control systems affected by the deviating data are transferred into a safe operating mode.
 6. A motor vehicle brake system characterized by means for carrying out the steps of a method as claimed in claim 1, and/or at least one electronic circuit arrangement (2) as claimed in one of claims 2 to
 5. 7. A motor vehicle comprising an electronic circuit arrangement (2), in particular a safety control unit, as claimed in one of claims 2 to 5, and/or a motor vehicle brake system as claimed in claim 6, and/or means for carrying out the steps of a method as claimed in claim
 1. 8. The use of an electronic circuit arrangement (2) for the redundant signal processing of a safety-relevant application, characterized in that the electronic circuit arrangement (2) is designed as claimed in one of claims 2 to 5, or the electronic circuit arrangement (2) for the redundant signal processing is used in a motor vehicle brake system as claimed in claim 6, and/or is used in a motor vehicle as claimed in claim
 7. 